<!-- 19语义化标签
    (1)无实意布局标签(没有显示效果，常用)
    1.<div>内容</div>(独占一行)
    2.<span>内容</span>(不独占一行)
    (2)有实意布局标签(手机端网页)
    1.header(头部)
    2.nav(导航)
    3.footer(尾部)
    4.section(区块)
    5.article(文章)
    6.aside(侧边栏)
-->

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <div>这是div标签</div>
    <span>这是span标签</span>

    <header>头部</header>
    <nav>导航</nav>
    <footer>尾部</footer>
    <section>区块</section>
    <article>文章</article>
    <aside>侧边栏</aside>
</body>
</html>